// Package kit
// Reference: https://github.com/puzpuzpuz/xsync/blob/main/util.go
package kit

import (
	"runtime"
	_ "unsafe"
)

const (
	// cacheLineSize is used in paddings to prevent false sharing;
	// 64B are used instead of 128B as a compromise between
	// memory footprint and performance; 128B usage may give ~30%
	// improvement on NUMA machines.
	cacheLineSize = 64
)

// NextPowOf2 computes the next highest power of 2 of 32-bit v.
// Source: https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
func NextPowOf2(v uint32) uint32 {
	if v == 0 {
		return 1
	}
	v--
	v |= v >> 1
	v |= v >> 2
	v |= v >> 4
	v |= v >> 8
	v |= v >> 16
	v++
	return v
}

func Parallelism() uint32 {
	maxProcs := uint32(runtime.GOMAXPROCS(0))
	numCores := uint32(runtime.NumCPU())
	if maxProcs < numCores {
		return maxProcs
	}
	return numCores
}

func Cheaprand() uint32 {
	return runtime_cheaprand()
}

//go:noescape
//go:linkname runtime_cheaprand runtime.cheaprand
func runtime_cheaprand() uint32
